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On 8/22/2013 1:35 PM, Randy Lauff wrote:
> They are not uncommon here in Antigonish,
* they're studied by Ken & Janet Storey at Carleton Univeristy -
http://http-server.carleton.ca/~kbstorey/insects.htm
"LIFE HISTORIES of GOLDENROD GALL INSECTS - Eurosta solidaginis (Fitch)
(Diptera, Tephritidae) is the larva of the goldenrod gall fly. Eggs are
laid in the growing tips of goldenrod plants in the spring and when they
hatch the larvae bore into the center of the stem and start to eat.
Secretions of the larvae mimic plant hormones and cause the plant to
form a ball gall around them and to stock the inside of the gall with
cells that are high in nutrients which the larvae eat. Third instar
larvae reach maximum size by early autumn. They bore a tunnel out to
near the surface of the gall (leaving just the epithelium layer) and
then settle back into the center of the gall to spend the winter. Downy
woodpeckers and chickadees will tap on galls until they find this tunnel
and then dive in the get the juicy larva which is a high fat winter
treat for them. Once settled in the center of the gall, the larvae
respond to autumn cues (shorter days, cooler temperatures, senescence of
the plant) by preparing for winter. They accumulate 2 cryoprotectants,
glycerol and sorbitol, and increase the supercooling point of their body
fluids by adding ice nucleators that stimulate freezing of the larvae
whenever temperature drops below about -8 to -10°C. The larvae survive
freezing and can endure the conversion of up to about 65 % of their
total body water in the extracellular ice. They endure multiple
freeze/thaw cycles over the winter and can survive to at least -30°C in
southern Canada. In late March and April, the larvae begin to break down
their cryoprotectants and get ready to pupate in late April. After 2-3
weeks, the adults hatch, walk up the tunnel, push their way through the
surface skin and then set off to start the cycle again."
I've written to the Storeys to see what they know about northern range
limits of the species, and if any increase of the range has been
observed with warming temperatures.
fred.
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Frederick W. Schueler & Aleta Karstad
Bishops Mills Natural History Centre - http://pinicola.ca/bmnhc.htm
Mudpuppy Night in Oxford Mills - http://pinicola.ca/mudpup1.htm
Daily Paintings - http://karstaddailypaintings.blogspot.com/
RR#2 Bishops Mills, Ontario, Canada K0G 1T0
on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
(613)258-3107 <bckcdb at istar.ca> http://pinicola.ca/
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